[www-scripts] Clang Attribute Doc Update: ERROR

[root via www-scripts]

UPDATING LLVM SOURCES
HEAD is now at 9bb2b4f [AMDGPU] Add alignment check for v3 to v4 load type promotion
>From https://github.com/llvm/llvm-project
 * branch            master     -> FETCH_HEAD
   9bb2b4f..d6aa4aa  master     -> origin/master
First, rewinding head to replay your work on top of it...
Fast-forwarded master to d6aa4aa29a25fac45ed250dd34cdbf8dbe8c0eb7.
CMake Error at CMakeLists.txt:3 (cmake_minimum_required):
  CMake 3.13.4 or higher is required.  You are running version 3.7.1


-- Configuring incomplete, errors occurred!